The invention relates to a method for the production of a number of coiled foil rolls, wherein the foils are reinforced in their edge region by folding. Furthermore, the invention relates to a device for the production of a number of coiled foil rolls.
It is a known solution at the production and coiling of plastic foils that the plastic foil which comes from a foil producing device, for example an extruder, is delivered to a spooling device to prepare it for the further handling and especially for the transport.
Thereby, it is known for example from DE 600 15 903 T2 or from EP 0 638 505 B1 to carry out the coiling in such a manner that during coiling the lateral end regions of the foil are crimped over. By doing so it can be reached that the sensitive lateral regions of the foil are much more mechanical stable as it would be in the case of a not crimped foil.
To make sure that the coiled foil with crimped lateral region becomes not too thick in the two lateral regions it is furthermore known to superpose the coiling device an oscillating transversal movement during the coiling process (changing of the spooling device). Such a solution is shown for example in EP 0 878 425 B1.
Furthermore, it is also known to cut several lamellar partial foils (foil section or “use”) from a delivered foil which extends along a whole width, wherein the single foil sections are then coiled respectively. This is disclosed for example in U.S. Pat. No. 8,221,298 B2.
Further solutions concerning the mentioned process are shown in U.S. Pat. No. 8,100,356 B2 and U.S. Pat. No. 5,531,393.
It is detrimental at some of the pre-known solutions that it is not possible to flexibly cut and coil several partial uses, i.e. foil sections, directly in an inline process, i.e. coming from the extruder. Rather, it is provided here that the coiling takes place in a subsequent process (i.e. offline). Insofar, methods and devices are concerned here which are basing only on a foil which is cut as a “single use”.
If the edges are reinforced, i.e. doubled and crimped over respectively, a thickening in the lateral regions occur (“bone”) as already mentioned, because the foil is doubled in terms of thickness in the region of the crimping and here becomes thick correspondingly. So, disadvantages result also at the further processing like increased outer dimensions of the coiled foil which is detrimental with respect for example to the volume of the packaging, to a blocking of the foil and to a higher pressure onto the coiling sleeve respectively. To allow a better coiling of the edges a second subsequent process for the oscillation of the foil is normally necessary.
It is common in all pre-known solutions that the width of the foil sections can be changed only in a difficult way or cannot be changed at all. Furthermore, it is hardly possible to change the extent of the edge reinforcement, i.e. of the folded region.